<template>
    <a-table
            :rowKey="rowKey"
            :columns="columns"
            :dataSource="dataSource"
            :expandedRowKeys="expandedRowKeys"
            v-bind="tableAttrs"
            v-on="$listeners"
            @expand="handleExpand"
            @expandedRowsChange="expandedRowKeys=$event">

        <template v-for="(slotItem) of slots" :slot="slotItem" slot-scope="text, record, index">
            <slot :name="slotItem" v-bind="{text,record,index}"></slot>
        </template>

    </a-table>
</template>

<script>
import { getAction } from '@/api/manage'

export default {
  name: 'JTreeTable',
  props: {
    rowKey: {
      type: String,
      default: 'id'
    },
    // 根据什么查询，如果传递 id 就根据 id 查询
    queryKey: {
      type: String,
      default: 'parentId'
    },
    queryParams: {
      type: Object,
      default: () => ({})
    },
    // 查询顶级时的值，如果顶级为0，则传0
    topValue: {
      type: String,
      default: null
    },
    columns: {
      type: Array,
      required: true
    },
    url: {
      type: String,
      required: true
    },
    childrenUrl: {
      type: String,
      default: null
    },
    tableProps: {
      type: Object,
      default: () => ({})
    },
    /** 是否在创建组件的时候就查询数据 */
    immediateRequest: {
      type: Boolean,
      default: true
    },
    condition: {
      type: String,
      default: '',
      required: false
    }
  },
  data() {
    return {
      dataSource: [],
      expandedRowKeys: []
    }
  },
  computed: {
    getChildrenUrl() {
      if (this.childrenUrl) {
        return this.childrenUrl
      } else {
        return this.url
      }
    },
    slots() {
      let slots = []
      for (let column of this.columns) {
        if (column.scopedSlots && column.scopedSlots.customRender) {
          slots.push(column.scopedSlots.customRender)
        }
      }
      return slots
    },
    tableAttrs() {
      return Object.assign(this.$attrs, this.tableProps)
    }
  },
  watch: {
    queryParams: {
      deep: true,
      handler() {
        this.loadData()
      }
    }
  },
  created() {
    if (this.immediateRequest) this.loadData()
  },
  methods: {

    /** 加载数据*/
    loadData(id = this.topValue, first = true, url = this.url) {
      this.$emit('requestBefore', { first })

      if (first) {
        this.expandedRowKeys = []
      }

      let params = Object.assign({}, this.queryParams || {})
      params[this.queryKey] = id
      if (this.condition && this.condition.length > 0) {
        params['condition'] = this.condition
      }

      return getAction(url, params).then(res => {
        let list = []
        if (res.result instanceof Array) {
          list = res.result
        } else if (res.result.records instanceof Array) {
          list = res.result.records
        } else {
          throw '返回数据类型不识别'
        }
        let dataSource = list.map(item => {
          // 判断是否标记了带有子级
          if (item.hasChildren === true) {
            // 查找第一个带有dataIndex的值的列
            let firstColumn
            for (let column of this.columns) {
              firstColumn = column.dataIndex
              if (firstColumn) break
            }
            // 定义默认展开时显示的loading子级，实际子级数据只在展开时加载
            let loadChild = { id: `${item.id}_loadChild`, [firstColumn]: 'loading...', isLoading: true }
            item.children = [loadChild]
          }
          return item
        })
        if (first) {
          this.dataSource = dataSource
        }
        this.$emit('requestSuccess', { first, dataSource, res })
        return Promise.resolve(dataSource)
      }).finally(() => this.$emit('requestFinally', { first }))
    },

    /** 点击展开图标时触发 */
    handleExpand(expanded, record) {
      // 判断是否是展开状态
      if (expanded) {
        // 判断子级的首个项的标记是否是“正在加载中”，如果是就加载数据
        if (record.children[0].isLoading === true) {
          this.loadData(record.id, false, this.getChildrenUrl).then(dataSource => {
            // 处理好的数据可直接赋值给children
            if (dataSource.length === 0) {
              record.children = null
            } else {
              record.children = dataSource
            }
          })
        }
      }
    }

  }
}
</script>

<style scoped>

</style>
